Large flexible fabric bags for containing and transporting flowable granular or powdered bulk material such as chemicals, minerals, foodstuffs, agricultural products, pharmaceutical and cosmetic ingredients and the like have been used for many years and their use is becoming increasingly more popular. This is due to their relatively low cost and the fact that when the bags are empty, they take up very little space and are relatively light in weight. When filled, the flexible bulk containers may carry a cubic meter or more of material and may weigh in excess of two tons.
The bags used for such purposes have to fulfill several practical requirements. It is necessary for the bags to be able to sustain heavy loads and, at the same time, be readily foldable or collapsible to a compact and relatively flat form when emptied. It is also important that such bags be designed so that, when filled, they can be easily handled, and are generally free standing and capable of being stacked vertically one upon another. Furthermore, depending upon the type of material being shipped, some fabric bulk bags may be required to be moisture proof, water resistant and/or hygienic, or requirements may be such that the contents must be sealed for the purpose of purity, in which case a polyethylene or the like liner is provided.
A variety of bags and bag constructions have been suggested and used as flexible bulk containers such as disclosed, for example, in U.S. Pat. Nos. 3,961,655; 4,113,146; 4,730,942; 4,781,472; 4,822,179; 4,909,410 and European patent publication No. 338,181. Although these bags and containers are common in the industry, there are several shortcomings which have been encountered and warrant further attention. For example, while the design, flexibility and light weight of many such bags renders them readily collapsible for convenient return by the user to the shipper for reuse, during the handling and storing of the bags they frequently come in contact with contaminants such as dirt, grease and the like which are deposited on or within the bags. This is particularly undesirable when the bag is filled with a foodstuff or pharmaceutical ingredient since protection from contamination is essential. Because fabric bulk containers in common use cannot be readily cleaned, disposal of the fabric bag is generally necessary when filling the same with materials that must be kept hygienically pure.
Some known bulk bags utilize a polyethylene or the like liner to contain particulate or granular material whereby the liner is insertable into the exterior fabric bag and the bag is formed with an opening or a spout at one end for discharging the contents. A common problem with such bags is the tendency for the particulate contents, when discharged, to draw the liner out of the bag. If the liner is not secured within the bag, the result is often that the liner itself will drop from the bag into the receiving container or bin and this could contaminate the contents which would be undesirable. It is, thus, common practice to secure the liner within the, bag, using techniques such as disclosed, for example, in U.S. Pat. Nos. 4,781,472, 4,874,258 and 4,946,241. However, due to the size of both the bags and liners, such known means for securing the liner within the bag are generally inconvenient and difficult to use.
Moreover, during the filling of such bags with a product, a great deal of dust can be generated which settles on exposed portions of the bag and liner, and as indicated, during the handling and storage of the bags, they frequently come in contact with contaminants such as dirt, grease, oil and the like against which the contents must be protected. In U.S. Pat. No. 4,909,410 there is suggested a bulk container with a removable protective cover for the outer surfaces of the container in the form of a skirt which is integrally secured to seams of the container. Such protective cover is removed from the bulk container to eliminate contaminants that may have been deposited on the external surface thereof but once removed, the container would have to be reconstructed for replacement of the protective cover and there is no other suggestion therein for cleaning the container itself for possible reuse.
Other devices such as removable covers have also been suggested for use with small hand-carried shopping bags and the like to protect the contents thereof against dirt and the elements. See, for example, U.S. Pat. Nos. 3,349,992 and 4,930,903. The shopping bags and the like containers employing such protective covers are substantially different in construction and use than the large bulk containers used for shipping and storage of bulk materials and the problems associated therewith are significantly different. Providing large, flexible bulk containers with a device which protects both the container surfaces and the contents thereof from being contaminated during filling, handling and storage would be particularly advantageous.
Applicant's prior patent, U.S. Pat. No. 5,192,134, discloses a flexible bulk container which can be thoroughly cleaned prior to use or reuse. This patent contemplates inserting a liner in between non-disposable top and bottom bulk bag components. The liner includes connecting means for connecting the liner within the top bag component. Replacing the liner after use requires that the top bulk bag component must be disconnected from the liner before the liner can be taken out of the container.